Tepotinib Inhibits Several Drug Efflux Transporters and Biotransformation Enzymes: The Role in Drug–Drug Interactions and Targeting Cytostatic Resistance In Vitro and Ex Vivo

Tepotinib is a novel tyrosine kinase inhibitor recently approved for the treatment of non-small cell lung cancer (NSCLC). In this study, we evaluated the tepotinib’s potential to perpetrate pharmacokinetic drug interactions and modulate multidrug resistance (MDR). Accumulation studies showed that tepotinib potently inhibits ABCB1 and ABCG2 efflux transporters, which was confirmed by molecular docking. In addition, tepotinib inhibited several recombinant cytochrome P450 (CYP) isoforms with varying potency. In subsequent drug combination experiments, tepotinib synergistically reversed daunorubicin and mitoxantrone resistance in cells with ABCB1 and ABCG2 overexpression, respectively. Remarkably, MDR-modulatory properties were confirmed in ex vivo explants derived from NSCLC patients. Furthermore, we demonstrated that anticancer effect of tepotinib is not influenced by the presence of ABC transporters associated with MDR, although monolayer transport assays designated it as ABCB1 substrate. Finally, tested drug was observed to have negligible effect on the expression of clinically relevant drug efflux transporters and CYP enzymes. In conclusion, our findings provide complex overview on the tepotinib’s drug interaction profile and suggest a promising novel therapeutic strategy for future clinical investigations.

Expressional Study of Permeability glycoprotein (P-gp) and Multidrug Resistance Protein 1 (MRP-1) in Drug-Resistant Mesial Temporal Lobe Epilepsy

About 30% of epileptic patients do not react to anti-epileptic drugs leading to refractory seizures. The pathogenesis of drug-resistance in Mesial Temporal Lobe Epilepsy (MTLE) is not completely understood. Increased activity of drug-efflux transporters might be involved, resulting in subclinical concentrations of the drug at the target site. The major drug-efflux transporters are permeability glycoprotein (P-gp) and multidrug-resistance associated protein-1 (MRP-1). The major drawback so far is the expressional analysis of transporters in equal numbers of drug-resistant epileptic tissue and age-matched non-epileptic tissue. We have studied these two transporters in the sclerotic hippocampal tissues resected from the epilepsy surgery (n=15) and compared their expression profile with the tissues resected from non-epileptic autopsy cases (n=15). Statistically significant over expression of both P-gp (p-value <0.0001) and MRP-1 (p-value 0.01) at gene and protein levels was found in the MTLE cases. The fold change of P-gp was more pronounced than MRP-1. Immunohistochemistry of patient group showed increased immunoreactivity of P-gp at blood brain barrier and increased reactivity of MRP-1 in parenchyma. The results were confirmed by confocal immunofluorescence microscopy. The study demonstrated that P-gp in association with MRP-1 might be responsible for the multi-drug resistance in epilepsy

Regulation of ABC Drug Efflux Transporters in Human T-Cells Exposed to an HIV Pseudotype

ATP-binding cassette (ABC) drug efflux transporters could contribute to low intracellular concentrations of antiretroviral drugs in HIV-1 cell reservoirs and sanctuary sites. Furthermore, the functional expression of these transporters could be induced in activated T-cells. Therefore, we investigated the expression of ABC drug efflux transporters in human T-cells exposed to an HIV pseudotype virus (pHIVNL4-3), and further examined the potential involvement of the mammalian target of rapamycin (mTOR) signaling pathway in regulating their expression following exposure to pHIVNL4-3. Additionally, we investigated the contribution of the drug efflux transporters to the inflammatory response following pHIVNL4-3-induced T-cell activation. Human peripheral blood mononuclear cells (PBMCs) were exposed to HIV-1 envelope glycoprotein gp120IIIB, pHIVNL4-3 and/or mTOR inhibitors. The expression of ABC transporters, T-cell activation marker CD69, mTOR and pHIVNL4-3 was assessed in CD4+ T-cells by Flow cytometry. mRNA and protein levels of proinflammatory cytokines (IL6, TNFα and INFγ) were examined in PBMCs by qPCR and ELISA analyses, respectively, following exposure to pHIVNL4-3 with or without inhibitors of mTOR or ABC transporters. The expression of ABC transporters (P-glycoprotein, breast cancer resistance protein and multi-drug resistance associated protein-1) was significantly increased in CD4+ T-cells exposed to pHIVNL4-3. Treatment with mTOR inhibitors attenuated pHIVNL4-3-induced transporter expression, as well as mRNA and protein levels of IL6, TNFα and INFγ. Additionally, inhibition of P-gp or MRP1 activity resulted in lower concentrations of proinflammatory cytokines in supernatants of PBMC exposed to pHIVNL4-3. Herein we present novel data demonstrating that upregulation of ABC drug efflux transporters could involve the mTOR signaling pathway in CD4+ T-cells exposed to an HIV pseudotype. These transporters could limit antiretroviral drug penetration in HIV target T-cells. Furthermore, ABC transporters could potentially contribute to HIV-associated proinflammatory cytokine secretion.

Combating HIV-1 by Targeting Drug Efflux Transporters on the Macrophage Reservoir

Introduction. HIV-1 eradication has not been achieved so far due to the existence of the cellular reservoir in which the virus can reside and replicate even under antiretroviral drug therapy (ART). Infected macrophages, which represent a long-term viral reservoir have been shown to lead to viral rebound independently. In response to the environmental stimuli, macrophages can be polarized into different phenotypes: the pro-inflammatory M1 and the anti-inflammatory M2. Tobacco smoking and alcohol drinking, which are prevalent among people who are living with HIV-1, have been shown to promote HIV-1 progression and decrease the efficacy of antiretroviral drugs. A commonly used macrolide antibiotic azithromycin (AZM) has been shown to shift macrophage polarization in a murine macrophage cell line. In the previous research, we found that drug efflux transporters expressed differently between macrophage phenotypes. In this dissertation, we examined the effects of CSC, ethanol exposure, and AZM on the expression and function of clinically relevant drug efflux transporters, viral suppression of antiretroviral drugs, and macrophage polarization. Methods. The human monocytic cell lines U937 and the U1 cell line, which is derived from HIV-1 infected U937, were used and polarized to the M1 and M2 macrophages. Cells with the treatment of CSC, ethanol, and AZM were harvested for downstream analysis including macrophage polarization, oxidative stress, cytokine production, transporter expression and function, and viral suppression. Cells treated with IKK-16, an inhibitor of the NF-κB signaling pathway, were harvested for the analysis of transporter expression and function. Protease inhibitor lopinavir (LPV) was used to suppress viral replication and the intracellular LPV was measured using LC-MS/MS. Results. Cigarette smoke condensate (CSC) and AZM shifted M1 macrophage polarization to M2 while having minimal effects on the M2 macrophage polarization. Inhibiting macrophage subset-specific transporters significantly increased intracellular antiretroviral drug (ARV) concentrations and drug efficacy. Neither CSC nor ethanol had any effect on the transporter inhibition-mediated viral reduction. AZM modulated the expression of major drug efflux transporters in both macrophage subsets and increased intracellular ARV concentration in M2 macrophages. NF-κB and JNK are involved in the M1 macrophage polarization shift and NF-κB was also shown to regulate major transporter expression. Conclusion. Modulating the expression and function of macrophage subset-specific transporter expression can increase intracellular ARV concentration and drug efficacy of viral suppression. Targeting subset-specific transporter may be an effective way to increase intracellular ARV concentration in the macrophage reservoir.

Suppression of HIV-1 Viral Replication by Inhibiting Drug Efflux Transporters in Activated Macrophages

Background: Ethanol has been shown to increase oxidative stress, drug efflux transporter expression, and promote HIV progression. Macrophages, which express drug efflux transporters, serve as an essential sanctuary site for HIV. The antiretroviral drug lopinavir, a protease inhibitor, is a substrate of the drug efflux transporters P-glycoprotein and multi-drug resistance-associated protein 1. The NF-κB signaling pathway is associated with inflammation and drug efflux transporter expression. Objective: Examine the effects of ethanol on drug efflux transporters and HIV replication of macrophages. Develop strategies to increase efficacy of protease inhibitor. Methods: The expression of PGP and MRP1 was examined with western blot. The NF- κB inhibition was assessed with nuclear western blot. LC-MS/MS and p24 ELISA were used to assess intracellular LPV and viral replication. Results: Ethanol at 40mM slightly increased drug efflux transporter PGP and MRP1 expression in activated macrophages. IKK-16, a NF- κB inhibitor, counteracted the increased transporter expression caused by ethanol exposure. MK571, a MRP1 inhibitor, and IKK-16 significantly increased intracellular LPV concentration with or without ethanol treatment. MK571 significantly increased LPV efficacy in suppressing viral replication with or without ethanol treatment. A decreasing trend and a significant decrease were observed with IKK-16+LPV treatment compared with LPV alone in the no ethanol treatment and ethanol treatment groups, respectively. Conclusion: In activated macrophages, inhibiting drug efflux transporter MRP1 activity and reducing its expression may represent a promising approach to suppress viral replication by increasing intracellular antiretroviral concentrations. However, different strategies may be required for ethanol-related vs. untreated groups.

Ensartinib (X-396) Effectively Modulates Pharmacokinetic Resistance Mediated by ABCB1 and ABCG2 Drug Efflux Transporters and CYP3A4 Biotransformation Enzyme

Ensartinib (X-396) is a promising tyrosine kinase inhibitor currently undergoing advanced clinical evaluation for the treatment of non-small cell lung cancer. In this work, we investigate possible interactions of this promising drug candidate with ATP-binding cassette (ABC) drug efflux transporters and cytochrome P450 biotransformation enzymes (CYPs), which play major roles in multidrug resistance (MDR) and pharmacokinetic drug-drug interactions (DDIs). Accumulation studies showed that ensartinib is a potent inhibitor of ABCB1 and ABCG2 transporters. Additionally, incubation experiments with recombinant CYPs showed that ensartinib significantly inhibits CYP3A4 and CYP2C9. Subsequent molecular docking studies confirmed these findings. Drug combination experiments demonstrated that ensartinib synergistically potentiates the antiproliferative effects of daunorubicin, mitoxantrone, and docetaxel in ABCB1, ABCG2, and CYP3A4-overexpressing cellular models, respectively. Advantageously, ensartinib’s antitumor efficiency was not compromised by the presence of MDR-associated ABC transporters, although it acted as a substrate of ABCB1 in Madin-Darby Canine Kidney II (MDCKII) monolayer transport assays. Finally, we demonstrated that ensartinib had no significant effect on the mRNA-level expression of examined transporters and enzymes in physiological and lung tumor cellular models. In conclusion, ensartinib may perpetrate clinically relevant pharmacokinetic DDIs and modulate ABCB1-, ABCG2-, and CYP3A4-mediated MDR. The in vitro findings presented here will provide a valuable foundation for future in vivo investigations.